Receiver operating characteristic curves for comparison of serial neutrophil band forms and C reactive protein in neonates at risk of infection

The Value of Perinatal Factors, Blood Biomarkers and Microbiological Colonization Screening in Predicting Neonatal Sepsis

Background: Neonatal sepsis is one of the most important causes of elevated morbidity and mortality rates in neonatal intensive care units worldwide. While the clinical manifestations of neonatal sepsis tend to be nonspecific, its rapid development and life-threatening potential call for reliable markers for early detection. Methods: We conducted a retrospective single-center study including all neonates suspected of having developed neonatal sepsis from 2013 to 2016. Perinatal and clinical characteristics as well as microbiological and laboratory findings were evaluated. Neonatal sepsis was defined as either culture-proven sepsis (positive blood culture) or clinical sepsis (at least one symptom and elevated C-reactive protein (CRP) concentrations within 72 h with negative blood culture). We further differentiated between early-onset (EOS) and late-onset (LOS) sepsis. Results: Microbiological colonization screening by throat and rectal swabs frequently did not detect the organism that subsequently caused the sepsis. Depending on the age of the newborn with sepsis (EOS or LOS), associations between different anamnestic and clinical factors (prenatal or postnatal ones) were found. In particular, the central−peripheral temperature difference showed a strong association with LOS. Laboratory results useful for the early detection of neonatal sepsis included interleukin-6 (IL-6) and CRP concentrations. Conclusions: Elevated IL-6 >100 ng/L was a strong marker for neonatal sepsis. When choosing the antibiotics for treatment, data from microbiological colonization screening should be considered but not solely relied on. Some indicators of infection also depended on postnatal age.

The Risk Factors of Bacterial Meningitis in Late-Onset Neonatal Sepsis

BACKGROUND: Neonatal bacterial meningitis has a significant contribution on neonatal morbidity and mortality. It is the most common complication of late-onset neonatal sepsis. An understanding of the risk factors for bacterial meningitis in late-onset neonatal sepsis is required to provide comprehensive management. AIM: To identify the risk factors of bacterial meningitis in late-onset neonatal sepsis. METHODS: This is an analytical study with a case–control design, conducted in May 2019-February 2021, involving neonates aged 4–28 days who suffered from late-onset neonatal sepsis in Level II and III Neonatal Care Unit, Sanglah General Hospital Denpasar. Statistical analysis was performed using Chi-square and logistic regression. RESULTS: A total of 54 patients were analyzed in this study. The mean age of subjects with neonatal bacterial meningitis was 13 days and the majority of them were male (51.9%). The risk factor of bacterial meningitis in late-onset neonatal sepsis was gestational age <37 weeks with odds ratio 4.22 (95% confidence interval 1.28–13.86, p = 0.01). There was no significant association of birth weight <2500 g, neonatal asphyxia, and invasive procedure on neonatal bacterial meningitis. CONCLUSION: Gestational age <37 weeks is a risk factor for bacterial meningitis in late-onset neonatal sepsis.

Neonatal Sepsis

Neonatal sepsis is associated with severe morbidity and mortality in the neonatal period. Clinical manifestations range from subclinical infection to severe local or systemic infection. Neonatal sepsis is divided into three groups as early-onset neonatal sepsis, late-onset neonatal sepsis and very late-onset neonatal sepsis according to the time of the onset. It was observed that the incidence of early-onset neonatal sepsis decreased with intrapartum antibiotic treatment. However, the incidence of late-onset neonatal sepsis has increased with the increase in the survival rate of preterm and very low weight babies. The source of the causative pathogen may be acquisition from the intrauterine origin but may also acquisition from maternal flora, hospital or community. Prematurity, low birth weight, chorioamnionitis, premature prolonged rupture of membranes, resuscitation, low APGAR score, inability to breastfeed, prolonged hospital stay and invasive procedures are among the risk factors. This article reviews current information on the definition, classification, epidemiology, risk factors, pathogenesis, clinical symptoms, diagnostic methods and treatment of neonatal sepsis.

C-reactive protein for diagnosing late-onset infection in newborn infants

BACKGROUND

Late-onset infection is the most common serious complication associated with hospital care for newborn infants. Because confirming the diagnosis by microbiological culture typically takes 24 to 48 hours, the serum level of the inflammatory marker C-reactive protein (CRP) measured as part of the initial investigation is used as an adjunctive rapid test to guide management in infants with suspected late-onset infection.

OBJECTIVES

To determine the diagnostic accuracy of serum CRP measurement in detecting late-onset infection in newborn infants.

SEARCH METHODS

We searched electronic databases (MEDLINE, Embase, and Science Citation Index to September 2017), conference proceedings, previous reviews, and the reference lists of retrieved articles.

SELECTION CRITERIA

We included cohort and cross-sectional studies evaluating the diagnostic accuracy of serum CRP levels for the detection of late-onset infection (occurring more than 72 hours after birth) in newborn infants.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed eligibility for inclusion, evaluated the methodological quality of included studies, and extracted data to estimate diagnostic accuracy using hierarchical summary receiver operating characteristic (SROC) models. We assessed heterogeneity by examining variability of study estimates and overlap of the 95% confidence interval (CI) in forest plots of sensitivity and specificity.

MAIN RESULTS

The search identified 20 studies (1615 infants). Most were small, single-centre, prospective cohort studies conducted in neonatal units in high- or middle-income countries since the late 1990s. Risk of bias in the included studies was generally low with independent assessment of index and reference tests. Most studies used a prespecified serum CRP threshold level as the definition of a 'positive' index test (typical cut-off level between 5 mg/L and 10 mg/L) and the culture of a pathogenic micro-organism from blood as the reference standard.At median specificity (0.74), sensitivity was 0.62 (95% CI 0.50 to 0.73). Heterogeneity was evident in the forest plots but it was not possible to conduct subgroup or meta-regression analyses by gestational ages, types of infection, or types of infecting micro-organism. Covariates for whether studies used a predefined threshold or not, and whether studies used a standard threshold of between 5 mg/L and 10 mg/L, were not statistically significant.

AUTHORS' CONCLUSIONS

The serum CRP level at initial evaluation of an infant with suspected late-onset infection is unlikely to be considered sufficiently accurate to aid early diagnosis or select infants to undergo further investigation or treatment with antimicrobial therapy or other interventions.

Procalcitonin and valuable clinical symptoms in the early detection of neonatal late-onset bacterial infection

AIM

To evaluate which clinical symptoms indicate proven neonatal bacterial infection (NBI) and whether measuring procalcitonin aside from C-reactive protein and interleukin 6 improves sensitivity and specificity in diagnosis.

METHODS

In a prospective observational study, clinical symptoms and procalcitonin, C-reactive protein and interleukin 6 were simultaneously determined from the 4th day of life in 170 preterm and term neonates at the first time of suspicion of NBI. Proven NBI was defined as a positive culture of otherwise sterile body fluids or radiologically verified pneumonia in combination with elevated inflammatory markers.

RESULTS

Fifty-eight (34%) patients were diagnosed with proven late-onset NBI. In case of proven NBI, odds ratio and 95% confidence intervals were 2.64 (1.06-6.54) for arterial hypotension, 5.16 (2.55-10.43) for feeding intolerance and 9.18 (4.10-20.59) for prolonged capillary refill. Sensitivity of combined determination of C-reactive protein (>10 mg/L) and interleukin 6 (>100 pg/mL) was 91.4%, specificity 80.4%, positive predictive value 70.7% and negative predictive value 94.7%. The additional determination of procalcitonin (>0.7 ng/mL) resulted in 98.3%, 65.2%, 58.8% and 98.6%, respectively.

CONCLUSION

Arterial hypotension, feeding intolerance and especially prolonged capillary refill indicate proven neonatal late-onset bacterial infection, even at the time of first suspicion. Additional measurement of procalcitonin does indeed improve sensitivity to nearly 100%, but is linked to a decline in specificity. Nevertheless, in the high-risk neonatal population, additional procalcitonin measurement can be recommended because all infants with NBI have to be identified.

Diagnosis and management of bacterial infections in the neonate

Perinatally acquired bacterial neonatal sepsis is a low-incidence,high-risk disease. Although incidence of the most common etiology,group B Streptococcus, has been reduced by prophylactic strategies,neonatal sepsis has not been eradicated, and vigilance must remain high. Accurate diagnosis is difficult: signs and symptoms are hard to distinguish from other causes of neonatal distress, and definitive diagnostic tests are not available. The clinician must make a judgment call, considering the perinatal history, the constellation of signs and symptoms, and the results of existing diagnostic tests,before neonatal sepsis can diagnosed or excluded. With diagnosis,knowledge of the specific disease states and clinical algorithms for management aid in formulating a plan of treatment with antimicrobial agents and supportive care.

Immature granulocyte measurement using the Sysmex XE-2100. Relationship to infection and sepsis

We determined the usefulness of immature granulocyte measurement as a predictor of infection or positive blood culture and compared the results with total WBC count and absolute neutrophil count (ANC). Blood samples from 102 infected and 69 noninfected patients were analyzed using the Sysmex XE-2100 automated blood cell counter (Sysmex, Kobe, Japan). The percentage of immature granulocytes was significantly higher in infected than in noninfected patients and in patients with positive than patients with negative blood cultures. Receiver operating characteristic curves showed that the percentage of immature granulocytes was a better predictor of infection than the WBC count and comparable to the ANC. Automated immature granulocyte measurements reflect a biologically and clinically relevant phenomenon but are not sensitive enough to be used as screening assays for prediction of infection or bacteremia. However, although infrequently encountered, a percentage of immature granulocytes of more than 3 was a very specific predictor of sepsis and might help expedite microbiologic laboratory evaluation of a subset of patients.

The role of C-reactive protein in the evaluation and management of infants with suspected sepsis

C-reactive protein (CRP) is a nonspecific, acute-phase protein that rises in response to infectious and noninfectious inflammatory processes. Good evidence exists to support the use of CRP measurements in conjunction with other established diagnostic tests (such as a white blood cell (WBC) count with differential and blood culture) to establish or exclude the diagnosis of sepsis in full-term or near-term infants. This article reviews the immunologic function of CRP and the history of CRP testing. The 3 methods for measuring CRP and the sensitivity and specificity of this diagnostic test are analyzed. Guidelines for the use of CRP in the evaluation and management of infants with suspected sepsis are presented. Quantitative serial CRP levels, obtained 24 hours after the onset of signs and symptoms of infection, with serial measurements 12 to 24 hours apart, offer the most sensitive and reliable information. At least 2 CRP levels, obtained 24 hours apart, with levels < or = 10 mg/L, are needed to identify infants unlikely to be infected. The use of CRP to exclude infection may allow clinicians to discontinue antibiotics at 48 hours in select infants, limiting extended unnecessary antibiotic exposure.

Reappraisal of C-reactive protein as a screening tool for neonatal sepsis

AIMS

To assess the usefulness of C-reactive protein (CRP) [either alone or in combination with a full blood examination (FBE) and microbiology of gastric aspirate] in predicting the diagnosis of neonatal sepsis compared with routinely available markers of infection.

METHODS

A prospective study of quantitative CRP, FBE, gastric aspirate and surface swab microscopy and culture in predicting neonatal sepsis in a level III perinatal referral hospital was performed.

RESULTS

Of 301 episodes evaluated over a 5-month period, there was a 5% rate of major (culture proven) sepsis (3% early onset, <72 hours) and 10% rate of modified sepsis. No single test alone was sufficiently reliable as an indicator of infection to be a satisfactory screening tool for early onset sepsis [CRP sensitivity 67%, negative predictive value (NPV) 86%, FBE sensitivity 63%, NPV 80%, gastric aspirate sensitivity 57%, NPV 83%].

CONCLUSION

The three-test combination had a sensitivity of 97%, NPV 98% and likelihood ratio of 49, thus providing a useful diagnostic tool.

Clinical utility of the band count

Enumeration of band neutrophils has a long clinical tradition as a diagnostic test for bacterial infection. Yet, the band count is a nonspecific, inaccurate, and imprecise laboratory test. Review of the literature provides little support for the clinical utility of the band count in patients greater than 3 months of age. The white blood cell count and the automated absolute neutrophil count are better diagnostic tests for adults and most children. Absolute numbers of bands are required for the Rochester criteria, a diagnostic algorithm for acutely ill, febrile children less than 3 months of age. No studies, however, assess the independent contribution of bands to the performance of the algorithm, or the use of the automated total neutrophil count as a replacement for the band count. Band counts also are required to calculate an immature to total neutrophil ratio (I:T ratio), an index widely used to aid in the diagnosis of neonatal sepsis. Studies, however, show a wide range of sensitivity and specificity for the I:T ratio, indicating variable performance. In the near future, rapid analysis of inflammatory factors, adhesion molecules, cytokines, neutrophil surface antigens, or even bacterial DNA may be superior alternative tests for the early diagnosis of sepsis.

Post-transfusion white cell count in the sick preterm neonate

OBJECTIVE

A previous report demonstrated post-transfusion leucocytosis as a potential confounding factor in the diagnosis of sepsis in critically ill adult patients. In We wished to establish if the same phenomenon occurred in the sick preterm neonate and whether this significantly altered the indices considered for potential neonatal infection.

METHODOLOGY

Transfusion and full blood count data in a level 3 neonatal intensive care unit were prospectively recorded for 3 months.

RESULTS

One hundred and fourteen transfusion events were recorded from 37 infants. Median white blood cell count increased 0.9 x 109/L (confidence interval (CI) 0.4-2.4) in the first 8 h following transfusion (P = 0.032). Median neutrophil count increased by 0.4 x 109/L (CI 0.1-1.7) in the same 8 h (P = 0.05). Median neutrophil left shift decreased 1.2% (CI 1.1-5.8%) over the 24 h post-transfusion. No change in band count was observed.

CONCLUSIONS

A mild post-transfusion white cell increase occurs in sick neonates. Because of the magnitude of effect, it is unlikely that this interesting physiological response would interfere with the diagnosis of sepsis in this population.

Role of infection in the development of acquired subglottic stenosis in neonates with prolonged intubation

OBJECTIVE

To examine whether clinically diagnosed infection correlates with subsequent development of subglottic stenosis in intubated neonates.

METHODS

Sixty-two neonatal infants intubated for more than 14 days were examined. Several risk factors for subglottic stenosis, including infection, duration of intubation, frequency of intubation, the size of the endotracheal tube etc., were evaluated by multiple logistic regression analysis.

RESULTS

Infection that occurred within 14 days of intubation showed a positive correlation with subsequent subglottic stenosis. The duration of intubation, frequency of intubation and the size of the endotracheal tube did not affect the development of subglottic stenosis. The majority of infections were considered to be respiratory tract infections, including pneumonia.

CONCLUSIONS

Infection occurring within 14 days of intubation is considered to be a risk factor for acquired subglottic stenosis in neonates intubated for more than 14 days. Prevention of infection within 14 days of intubation may reduce the incidence of subglottic stenosis in neonates.

Randomised controlled study of clinical outcome following trophic feeding

AIMS

To determine the effect of trophic feeding on clinical outcome in ill preterm infants.

METHODS

A randomised, controlled, prospective study of 100 preterm infants, weighing less than 1750 g at birth and requiring ventilatory support and parenteral nutrition, was performed. Group TF (48 infants) received trophic feeding from day 3 (0.5-1 ml/h) along with parenteral nutrition until ventilatory support finished. Group C (52 infants) received parenteral nutrition alone. "Nutritive" milk feeding was then introduced to both groups. Clinical outcomes measured included total energy intake and growth over the first six postnatal weeks, sepsis incidence, liver function, milk tolerance, duration of respiratory support, duration of hospital stay and complication incidence.

RESULTS

Groups were well matched for birthweight, gestation and CRIB scores. Infants in group TF had significantly greater energy intake, mean difference 41.4 (95% confidence interval 9, 73.7) kcal/kg p=0.02; weight gain, 130 (CI 1, 250) g p = 0.02; head circumference gain, mean difference 0.7 (CI 0.1, 1.3) cm, p = 0.04; fewer episodes of culture confirmed sepsis, mean difference -0.7 (-1.3, -0.2) episodes, p = 0.04; less parenteral nutrition, mean difference -11.5 (CI -20, -3) days, p = 0. 03; tolerated full milk feeds (165 ml/kg/day) earlier, mean difference -11.2 (CI -19, -3) days, p = 0.03; reduced requirement for supplemental oxygen, mean difference -22.4 (CI-41.5, -3.3) days, p = 0.02; and were discharged home earlier, mean difference -22.1 (CI -42.1, -2.2) days, p = 0.04. There was no significant difference in the relative risk of any complication.

CONCLUSIONS

Trophic feeding improves clinical outcome in ill preterm infants requiring parenteral nutrition.

Reduction of unnecessary antibiotic therapy in newborn infants using interleukin-8 and C-reactive protein as markers of bacterial infections

OBJECTIVE

To examine whether the determination of interleukin 8 (IL-8) and C-reactive protein (CRP) in neonates with suspected nosocomial bacterial infection (NBI) is feasible and cost-effective in reducing antibiotic therapy.

METHODS

Between April 1996 and May 1997, IL-8 was measured 260 times along with blood cultures, CRP, and immature-to-total-neutrophil (IT) ratio for suspected NBI in term and preterm neonates. All infants were retrospectively analyzed for NBI. Sensitivity, specificity, positive and negative predictive values, and 95% confidence intervals were calculated for IL-8, CRP, and IT ratio. Receiver-operating characteristic curves were analyzed to determine optimal thresholds. Between June 1997 and June 1998, IL-8 was measured 215 times in newborn infants with suspected NBI and the decision to start antibiotic therapy was based on increased IL-8 and/or CRP values. A cost-effectiveness analysis was performed and sensitivity, specificity, and receiver-operating characteristic curves were reevaluated.

RESULTS

At the first suspicion of NBI, the combination of IL-8 >/= 53 pg/mL and/or CRP >10 mg/L detected culture-proven NBI with 96% sensitivity. The combined culture-proven and clinical NBI were detected with 93% sensitivity and 80% specificity. The use of IL-8 reduced unnecessary antibiotic therapy for suspected NBI by 73% and was cost-effective when compared with initiating antibiotic therapy based on clinical signs alone or based on clinical signs and an increased IT ratio and/or CRP.

CONCLUSIONS

The combination of IL-8 and/or CRP is a reliable and early test for the diagnosis of NBI in newborn infants. Using the combination of IL-8 and/or CRP to restrict antibiotic therapy to truly infected infants reduces unnecessary antibiotic therapy and is cost-effective.

Comparison of procalcitonin with interleukin 8, C-reactive protein and differential white blood cell count for the early diagnosis of bacterial infections in newborn infants

OBJECTIVE

To evaluate procalcitonin (PCT) as a test for early diagnosis of bacterial infections (BI) in newborn infants and to compare the results of PCT with those of interleukin 8 (IL-8), C-reactive protein (CRP) and differential white blood cell count.

STUDY DESIGN

PCT was prospectively measured along with IL-8, CRP and differential white blood cell counts and blood cultures in 197 newborn infants at the first suspicion of bacterial infection. PCT, IL-8, CRP and differential white blood cell counts were analyzed for sensitivity, specificity and positive and negative predictive values after receiver operating characteristic curve analysis for best thresholds. The kinetics of PCT was determined in infants with and without BI.

RESULTS

Forty-six infants were diagnosed clinically as having BI, of whom 9 had BI with positive blood cultures. At a cutoff value of 0.50 microg/l, PCT detected combined culture-proved and clinical BI with a sensitivity of 57% (95% confidence interval, 41%, 71%) and a specificity of 66% (95% confidence interval, 57%, 74%). The combination of IL-8 > or =70 ng/l and/or CRP >10 mg/l achieved a sensitivity of 91% (95% confidence interval, 79%, 98%) and a specificity of 73% (95% confidence interval, 64%, 81%). PCT values of infected and not infected infants tended to rise for 24 h after initial evaluation and then decreased.

CONCLUSION

The combination of IL-8 and CRP is more reliable than PCT as a test for early diagnosis of BI in newborn infants.

Serial serum C-reactive protein levels in the diagnosis of neonatal infection

OBJECTIVE

To evaluate serial serum C-reactive protein (CRP) levels for diagnosis of neonatal infection.

SETTING

A regional intensive care nursery and two community intensive care nurseries.

METHODS

All neonates treated for suspected bacterial infection were prospectively evaluated using a standardized clinical pathway. Infants were categorized as having proven sepsis (bacteria isolated from blood, cerebrospinal fluid, or urine culture), probable sepsis (clinical and laboratory findings consistent with bacterial infection without a positive culture), or no sepsis (findings not consistent with sepsis), without consideration of CRP levels. Infants whose blood cultures yielded skin flora but who demonstrated no other signs of bacterial infection were not considered to have sepsis. CRP levels were determined at the initial evaluation and on each of the next two mornings. Sensitivity, specificity, predictive values, and likelihood ratios were calculated for the first (CRP #1), second (CRP #2), higher of the second and third (CRP #2 and #3), or highest of all three CRP levels (CRP x 3).

RESULTS

Sepsis was suspected within the first 3 days after birth in 1002 infants (early-onset) and on 184 occasions in 134 older infants (late-onset). There were 20 early-onset and 53 late-onset episodes of proven sepsis, and 74 early-onset and 12 late-onset episodes of probable sepsis. CRP #1 had sensitivities of 39.4% and 64.6% for proven or probable sepsis and 35.0% and 61.5% for proven sepsis in early-onset and late-onset episodes, respectively. CRP levels on the morning after the initial evaluation (CRP #2) had higher sensitivities (92. 9% and 85.0% for proven or probable sepsis and 78.9% and 84.4% for proven sepsis in early-onset and late-onset episodes, respectively), and normal results were associated with lower likelihoods of infection (likelihood ratios for normal results of 0.10 and 0.19 for proven or probable sepsis and 0.27 and 0.21 for proven sepsis, in early-onset and late-onset episodes, respectively). Three serial serum CRP levels had sensitivities of 97.8% and 98.1% for proven or probable sepsis and 88.9% and 97.5% for proven sepsis in early-onset and late-onset episodes, respectively. The negative predictive values for CRP x 3 were 99.7% and 98.7% for both proven or probable sepsis and for proven sepsis in early-onset and late-onset episodes, respectively. A CRP level obtained at the time of the initial evaluation can be omitted without significant loss of sensitivity or negative predictive value: the sensitivities of CRP #2 and #3 were 97.6% and 94.4% for proven or probable sepsis and 88.9% and 96.4% for proven sepsis in early-onset and late-onset episodes, respectively; negative predictive values were 99.7% both for proven and for proven or probable early-onset sepsis, 97.6% for proven or probable late-onset infection, and 98.8% for proven late-onset infection. Serial normal CRP levels were associated with a markedly reduced likelihood of infection as compared with that in the entire population before testing, with likelihood ratios ranging from 0.03 to 0.16 for the various subgroups. Maximum CRP levels >3 mg/dL had positive predictive values >20% for proven or probable early-onset infections and for proven or probable and proven late-onset infections, but only those >6 mg/dL had such a high positive predictive value for proven early-onset sepsis.

CONCLUSIONS

Serial CRP levels are useful in the diagnostic evaluation of neonates with suspected infection. Two CRP levels <1 mg/dL obtained 24 hours apart, 8 to 48 hours after presentation, indicate that bacterial infection is unlikely. The sensitivity of a normal CRP at the initial evaluation is not sufficient to justify withholding antibiotic therapy. The positive predictive value of elevated CRP levels is low, especially for culture-proven early-onset infections.

A prospective study on the relationship between intrapartum maternal group-B streptococcal concentration and signs of infection in neonates

OBJECTIVE

Our purpose was to examine the effects of intrapartum vaginal Group-B streptococcal (GBS) colonization on neonatal signs of infection.

STUDY DESIGN

We performed a quantitative GBS culture of vaginal specimens in 1,280 pregnancies within 24 hours before delivery and examined signs of neonatal infection within 48 hours after birth. Among them, 287 pregnant women had premature ruptures of membranes.

RESULTS

The rate of vaginal GBS colonization in groups with and without ruptured membranes was 22.0% and 11.3%, respectively. The incidence of neonates with signs of infection born to GBS-carrier women in each group was 28.6% and 8.8%, respectively. There were significant differences between the groups with regard to both the rate of colonization and the incidence of infection. Signs of neonatal infection increased in proportion to the maternal GBS concentration only in women with ruptured membranes.

CONCLUSION

This study suggests that there is an important association between maternal GBS concentration and mild neonatal infections after birth, especially in women with premature ruptures of membranes.

Comparison of C-reactive protein and white blood cell count with differential in neonates at risk for septicaemia

We prospectively compared the diagnostic value of C-reactive protein (CRP) and white blood cell counts for detection of neonatal septicaemia. Sensitivity and specifity in receiver operating characteristics, and positive and negative predictive value of CRP and white blood cell count were compared in 195 critically ill preterm and term newborns clinically suspected of infection. Blood cultures were positive in 33 cases. During the first 3 days after birth CRP elevation (sensitivity 75%, specifity 86%), leukopenia (67%/90%), neutropenia (78%/80%) and immature to total neutrophil count (I/T) ratio (78%/73%) were good diagnostic parameters, as opposed to band forms with absolute count (84%/66%) or percentage (79%/71%), thrombocytopenia (65%/57%) and toxic granulations (44%/94%). Beyond 3 days of age elevated CRP (88%/87%) was the best parameter. Increased total (84%/66%) or percentage band count (79%/71%) were also useful. Leukocytosis (74%/56%), increased neutrophils (67%/65%), I/T ratio (79%/47%), thrombocytopenia (65%/57%) and toxic granulations had a low specifity. The positive predictive value of CRP was 32% before and 37% after 3 days of age, that of leukopenia was 37% in the first 3 days.

CONCLUSION

During the first 3 days of life CRP, leukopenia and neutropenia were comparably good tests while after 3 days of life CRP was the best single test in early detection of neonatal septicaemia. Serial CRP estimations confirm the diagnosis, monitor the course of infection and the efficacy of antibiotic treatment.

Stethoscope contamination in the neonatal intensive care unit

The level of contamination of stethoscopes used in a neonatal intensive care unit was studied, along with the practices used for cleaning these items. A policy of alcohol cleaning was introduced and the effect of this change on the level of bacterial growth was observed after a six-week period. It was found that 71% of stethoscopes had a significant bacterial growth and that this was reduced to 30% after the cleaning procedure change (P < 0.05). Stethoscopes and other equipment are a potential source of nosocomial infection on the neonatal intensive care unit.

Clinical and bacteriological survey after change in aminoglycoside treatment to control an epidemic of Enterobacter cloacae

The effect of a change in the first line antibiotic treatment in a neonatal unit was studied. A total of 238 neonates (G1), admitted between 1 January and 31 July 1989, and treated with gentamicin, were compared with 398 (G2) admitted between 1 August 1989 and 31 July 1990 who received amikacin, in the combination of ampicillin plus an aminoglycoside. This change was implemented in an attempt to prevent the spread of an epidemic strain of Enterobacter cloacae resistant to third generation cephalosporins and all aminoglycosides, except amikacin. The change in treatment had no effect on the incidence of nosocomial infections [19.7% (G1) vs. 16.3% (G2) RR = 1.21 (0.86-1.70)], but the proportion of patients with nosocomial infections caused by the E. cloacae decreased (6.3% vs. 2.0% RR 3.14 CI 1.35-7.28). Certain trends in the bacterial ecology emerged: E. aerogenes and Enterococci increased in G2. The proportion of gentamicin-resistant strains such as E. cloacae or Staphylococci decreased and there was no increase in aminoglycoside-resistant strains, except in Escherichia coli, in which resistance to amikacin rose from 0 to 3%. This study illustrates the influence of antimicrobial therapy on the species and the resistance of strains isolated in nosocomial infections. It also highlights the need for epidemiologic surveillance, and poses the question of how best to modify antibiotic policy.

Prediction of chronic neonatal lung disease in very low birthweight neonates using clinical and radiological variables

There are good theoretical reasons for earlier intervention in neonates likely to develop chronic neonatal lung disease (CNLD). Very low birthweight (VLBW) neonates who receive artificial ventilation are at high risk of CNLD. A test was therefore developed to predict CNLD based on clinical and radiological information readily available at 7 days of age in VLBW neonates. Logistic regression analysis was used to identify those factors significantly and independently associated with CNLD. For each neonate it was possible to insert the value of the independent factors into the equation, providing a probability value between 0 and 1. By selecting different cut off values between 0 and 1, and knowing which neonates had developed CNLD, it was possible to assess the use of varying probability values as a predictive test for CNLD. The variation in these two parameters was graphically represented by a receiver operator characteristic (ROC) curve. The area under the ROC curve was used to represent the discriminatory capacity of the test over its full range of values. The maximum area under an ROC curve is unity. The area under the ROC curve was similar in a model with and without radiographic information (0.926 and 0.913 respectively) and was 0.937 in neonates from another hospital.

C-reactive protein as a diagnostic tool of sepsis in very immature babies

Three hundred and nine septic screens were performed on 123 consecutively admitted infants of < 30 weeks gestation. As part of the septic screen, serial quantitative measurements of C-reactive protein (CRP) were performed daily until discontinuation of antibiotic therapy. Complete blood counts were performed daily for the first 2 days of each septic episode. The babies had a mean birth weight of 1035.8 g s.d. 273.2 and a mean gestational age of 27 weeks s.d. 1.8. A CRP level of 10 mg/L or above was considered abnormal. Subsequently the receiver operator characteristic curve for CRP was constructed to demonstrate the ideal cut off value. Of the 309 septic screens, there were 51 instances of proven sepsis and 39 instances of deep culture negative sepsis. In the remaining 219, a diagnosis of proven or deep culture negative sepsis could not be made. On the first day of the septic episode CRP showed a sensitivity of 62.7%, specificity of 87.2% and negative predictive value of 92.2% for proven sepsis. There was a significant increase in the sensitivity (90.2%) and negative predictive value (97.7%) of CRP with a specificity of 80.6 when both day 1 and 2 estimations were combined. We conclude that when the CRP is elevated on day 1 and/or day 2, the diagnosis of sepsis is extremely likely and when the CRP is within normal limits on days 1 and 2 of the septic episode, neonatal sepsis can be confidently excluded and antibiotic therapy ceased.

C reactive protein and neutrophil band forms in neonates

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